1. Field of the Invention
The present invention relates to a spindle motor and a hard disk drive including the same.
2. Description of the Related Art
A hard disk drive (HDD), an information storage device, reads data stored on a disk or writes data to a disk using a read/write head.
The hard disk drive requires a disk drive capable of driving the disk. In the disk drive, a spindle motor is used.
The spindle motor has used a hydrodynamic bearing assembly. A shaft, a rotating member of the hydrodynamic bearing assembly, and a sleeve, a fixed member thereof, have lubricating fluid interposed therebetween, such that the shaft is supported by fluid pressure generated in the lubricating fluid.
Here, increases in the capacity of spindle motors and the thinning thereof have been gradually demanded. In accordance with thinness and miniaturization of spindle motors, bearing rigidity has been naturally weakened.
Bearing rigidity, an important factor in determining rotational characteristics of the spindle motor, is affected by an interval between dynamic pressure grooves, that is, a bearing span length.
That is, as the bearing span length increases, bearing rigidity increases, such that rotational characteristics of the spindle motor may be improved. Therefore, even in the case that capacity of the spindle motor is increased and the spindle motor is thinned, bearing rigidity should not be effected.
In addition, the lubricating fluid injected into the hydrodynamic bearing assembly may be leaked to the outside due to an impact or may be evaporated, such that an amount of lubricating fluid in a bearing may be decreased. Due to the above-mentioned phenomenon, the hydrodynamic bearing may not generate sufficient pressure, such that a limitation in terms of performance and a lifespan of the spindle motor may occur.
Therefore, research into technology allowing for bearing rigidity to be maintained in spite of promoting an increase in a capacitor of a spindle motor and thinness of the spindle motor, improving rigidity of the spindle motor so that an internal component of the spindle motor is not deformed even in the case that an external impact, or the like, is applied to the spindle motor, and securing a storage space for lubricating fluid to significantly increase performance and a lifespan of the spindle motor has been urgently demanded.